In a liquid material discharge device, there is a possibility that the viscosity of a liquid material may increase with the lapse of time, and that clogging may occur in a flow path or a nozzle inside a device body, or a discharge amount may change (mainly reduce). It is hence required to periodically clean the flow path in contact with the liquid material. The cleaning is essential particularly in a discharge device (see FIGS. 4 to 6) of type discharging the liquid material from a nozzle by the action of a mechanically-operated rod-like member because that type of discharge device generally has a complicated structure.
The discharge device is generally cleaned by a method of disassembling the discharge device into individual components, dipping each component, to which the liquid material adheres, in a solvent (cleaning fluid) prepared in a vessel of a relatively small volume, and cleaning the component with an ultrasonic cleaner. Such a method can be readily practiced without needing large-scaled equipment, but it has the following problems.
The first problem is concerned with time. Disassembling and assembling the discharge device take a time. The liquid material cannot be removed unless ultrasonic vibration is applied for a comparatively long time. In order to fully remove the liquid material, the cleaning has to be carried out several times while the solvent is replaced with fresh one. The second problem is concerned with effect of the cleaning. The liquid material having dissolved into the solvent may adhere to the component again. In other words, the liquid material may be not fully removed. The third problem is concerned with safety. Because the cleaning is basically performed manually, there is a risk that harmful substances (including the solvent and the liquid material) may contact the operator's body.
Another method is also known in which pipes are connected to the body and the nozzle of the discharge device without disassembling the discharge device, and the cleaning fluid is directly poured into them for cleaning.
For example, Patent Document 1 discloses a cleaning device for a functional droplet discharge head, which supplies a cleaning fluid to pass through a flow path in the head for cleaning of the flow path in the head, the device comprising a cleaning fluid tank that supplies the cleaning fluid, a cleaning fluid collection unit that recovers the cleaning fluid having passed through the flow path in the head, a cleaning fluid flow path through which the cleaning fluid is guided to flow from the cleaning fluid tank to the cleaning fluid collection unit through an introducing-portion connection joint and a cap, liquid feeding means that feeds the cleaning fluid through the cleaning fluid flow path, forced ventilation means that introduces air into the cleaning fluid flow path while forcedly supplying the air to pass therethrough, and control means that, after the end of the feeding of the cleaning fluid, drives the forced ventilation means to forcedly supply the air to pass through the cleaning fluid flow path.
Patent Document 2 discloses a nozzle cleaning device for a continuously-coating nozzle coater, featured in fabricating a cap that can accommodate a nozzle end portion of the nozzle coater including a nozzle, which has a slit-shaped nozzle opening formed at a nozzle tip for discharging a paint and to which a paint supply pipe is connected, the cap having a width wider than the nozzle opening, forming a paint drain hole in a region of the cap, which region is positioned to face the nozzle opening, and fixing a paint drain pipe to a portion of the paint drain hole, which portion is positioned outside the cap.